I have a handful of magnesium wheels, that leak air, at the bead (tire-sidewall/wheel connection). They are very slow leaks, but air leaks, none the less. I have verified that they do not leak from the beadlock screws or the Valve stem. Wheels are in decent shape otherwise, and wish to salvage and continue to use them.

Does anyone have a “trick up their sleeve” that I can use to Stop these leaks 100%, please?

You know that most racing tires leak air right through the rubber right? If they hold air for an hour that’s my minimum standard for sprint racing. Have you tried wire brushing or using 150 grit sandpaper. If you have some way to spin the wheel it makes it easy. You could also try a very thin layer of epoxy or JB weld.